Webb and Hubble image Whirlpool galaxy

On May 17, Live Science highlighted a composite view of the Whirlpool Galaxy, or Messier 51, built from James Webb Space Telescope and Hubble Space Telescope observations. The image was tied to a May 6 research release from ESA/Webb describing how astronomers are using the two observatories together to track how young star clusters emerge from the gas clouds that formed them. The underlying study, published in Nature Astronomy on May 7, analyzed thousands of clusters in four nearby galaxies and found that the most massive young clusters shed their natal gas faster than lower-mass ones. ### Why are Webb and Hubble both in this Whirlpool image? ESA/Webb said the two telescopes contribute different parts of the star-formation story. Webb can see into dusty gas clouds in infrared wavelengths, while Hubble’s optical data picks out clusters that have already emerged and become unobscured. The combined approach lets astronomers place young clusters on an evolutionary sequence rather than viewing only the beginning or the aftermath. (livescience.com) The PHANGS collaboration describes its HST-and-JWST imaging as a dataset designed to study star formation across nearby spiral galaxies from star clusters and molecular clouds up to full galactic disks. That broader survey framework is part of why a single M51 image can be used as an illustration of a larger analysis rather than as a standalone portrait. ### What exactly did astronomers measure in M51 and the other galaxies? (esawebb.org) Nature Astronomy said the team used Hubble Space Telescope and James Webb Space Telescope observations of thousands of young star clusters in four nearby galaxies: M51, M83, NGC 628 and NGC 4449. The paper said a substantial fraction of those clusters remain embedded in natal gas and are invisible at optical wavelengths, which is where Webb’s infrared view becomes critical. (phangs.stsci.edu) ESA/Webb said the researchers identified nearly 9,000 star clusters spanning different stages of development, from clusters just starting to emerge from birth clouds to fully unobstructed clusters seen in Hubble data. With Webb spectra and imaging, the team then estimated cluster ages and masses and measured how long surrounding material took to disperse. ### What did the study find about massive star clusters? (nature.com) The May 6 ESA/Webb release said the most massive star clusters emerge more quickly from the clouds they are born in. Nature Astronomy summarized the result as evidence that massive young clusters disperse natal gas faster than low-mass clusters, with implications for models of star formation and stellar feedback. ESA/Webb described stellar feedback as the winds, ultraviolet radiation and later supernova explosions from young stars that push gas away from a forming cluster. (esawebb.org) Because that gas is the raw material for later stars, measuring how quickly it is cleared helps researchers map where and when galaxies can keep forming stars. ### Why is the Whirlpool Galaxy a useful case? M51 lies about 27 million light-years away in Canes Venatici, ESA said, and interacts with its smaller companion NGC 5195. (esawebb.org) NASA and ESA both describe the Whirlpool’s spiral arms as active star-forming regions, with the interaction between the two galaxies helping shape the arms and trigger new star formation. The M51 panel released by ESA/Webb shows part of one spiral arm rather than the entire galaxy. (esawebb.org) ESA said the red and orange structures trace ionized gas, dust and complex molecules, while the bright compact sources inside those gas complexes are newly formed clusters. ### Where does this leave the research now? The PHANGS program says HST and JWST imaging for 74 spiral galaxies has been assembled through multiple treasury programs, giving astronomers a larger comparative sample beyond the four galaxies in the May 2026 paper. (esa.int) ESA/Webb’s May 6 release framed the M51 image as one piece of the FEAST observing program, which is aimed at studying stellar nurseries outside the Milky Way. (esawebb.org) Nature Astronomy lists the paper, “The emerging timescale of young star clusters regulated by cluster stellar mass,” as open access. Readers looking for the next step can find the full results there, while ESA/Webb and the PHANGS collaboration continue posting image releases and survey data tied to the same Hubble-and-Webb observing campaigns. (nature.com) (phangs.stsci.edu)